Optimization of Struvite Precipitation for Landfill Leachate Treatment

Sanitary landfill is the most preferred municipal solid waste disposal method. The production of highly polluted leachate is a major disadvantage of sanitary landfills. In this study, optimization of struvite precipitation to remove ammonium from landfill leachate was conducted by using Response Surface Methodology (RSM) and Central Composite Design (CCD). Optimum struvite precipitation conditions were determined based upon 11 runs performed in CCD. A second-order polynomial functional model was fitted well to the results. The statistical analysis showed that two independent variables which are molar rates of Mg/N and N/P had significant effects on the ammonium removal efficiency. Maximum ammonium removal efficiency was 99.8% at a molar rate of 1.20 for Mg/N and 1.27 for N/P for a constant 9.2 pH value. The obtained results revealed that struvite used as pretreatment in anaerobic process can be modelled by using RSM. And also, RSM can be used to optimize required ammonium removal efficiency for lower Mg/N and N/P molar ratio which affects the performance of pretreatment method that designed for an anaerobic process having 300:5:1 ratio for COD/N/P